While this invention does not necessarily involve lasers (although they could be optionally superposed onto my system) I immediately wondered in the early 1960's when lasers first appeared whether or not they could be used to heat fusionable materials to reaction temperatures. But it was not until early 1964 that I got a chance to construct a helium-neon laser with my own hands and to experiment with ruby lasers. Some of my associates at the former Maser Optics Co. Inc. of Boston were using ruby lasers to punch through refractory and very hard materials. It took them many shots and much repumping time between shots to get through even thin sheets of certain alloys with the early mw ruby lasers.
Already with a view toward laser implosion of fusionable material, I suggested to my associates that it might be quicker to split the beam and direct same from opposite sides of a sheet. My reasoning was that the momentum of material from one side would reinforce the ablation of the other. So for dual reasons I set up in one of the work rooms what I believe to be the world's first experiment to deliberately converge laser beams head-on with a view toward eventual laser implosion of fusionable pellets. With a (weak) 1 mw ruby laser I punched through uniform thicknesses of certain alloys including nichrome --with and without splitting the beam. When hitting the sheets from one side I made the beam take a pathway equal in optical thickness to that from both sides. I tried to equalize the ambient temperature for each approach. Indeed fewer shots were required when attacking the sheets from both sides simultaneously. Then I spent a few weeks informally sketching various spherical laser implosion systems including one combination laser-fusion system sharing the same (deuterium) gas.
In April, 1964, I telephoned the former Atomic Energy Commission and eventually proposed to Dr. Arthur Ruark, Head of the Thermonuclear Division, that lasers be used to spherically implode fusionable material. At that time fusion was still partly classified as secret by the U.S. Government, so Dr. Ruark could not discuss specific temperatures; but he did say that he seriously doubted that lasers (of that time or the immediate future) could produce the temperatures requisite for fusion. I argued that lasers are parallel, not point, sources of light, hence can be made as intense as one desires by merely making the amplifiers larger--all without violating any laws of thermodynamics. Dr. Ruark said that even so their efficiences were too low to result in a net energy yield from fusion. That point I could not argue with, except to say that perhaps lasers could be used only to start nuclear reactions and the reactant products could complete same. Dr. Ruark remained highly doubtful about the "pumping ratio" of lasers and concluded "write up your experiment, send it in and maybe we'll look at it again someday if lasers improve." Well, I wrote it up, got it witnessed by some of my associates, and still have the original for I did not send it to the AEC in view of the skepticism of the man who would pass judgment on its potential.
Three years later, in 1967, The AEC nonetheless funded a program at the Lawrence Laboratory at Livermore, Ca. to do precisely what I had suggested to Dr Ruark. No word was transmitted to me about the project. It was several years later that I read about the program--after fusion was entirely declassfied.
Meanwhile work in that program indicated that it was not the incident photons per se that moved the fusionable atoms inward, but rather it was the electrons knocked loose by the photons that imploded and caused the reactions. Consequently, I reasonsed that maybe electrons themselves could be accelerated directly into the pellets. After all electrons have more mass and momentum by far than photons and despite electrons' electrostatic repulsion for one another they can be focussed sharply onto a pellet 1 mm in diameter. However, on further analysis another approach looked even more promising.